In recent years, due to a rise in the environment consciousness and an increasing concern in depletion of petroleum resources in the future, a reduction in the fuel consumption of the vehicle is further required. Moreover, a rapid progress is observed in secondary cells (batteries) represented by a lithium-ion battery, and use of electric power as power for travel is actively attempted, such as that in an electric vehicle and a hybrid vehicle.
As the performance of the electric vehicle and the hybrid vehicle increases, the output density of a motor increases, and the calorific value increases. Thus, in order to cope with the increase in the calorific value, in addition to a reduction in the calorific value by means of an increase in efficiency of the motor and an increase in heat resistance of coils, magnets, and the like, various motor cooling methods are proposed.
For example, as one of the motor cooling methods, there is proposed such a method that, in a motor control apparatus including a clutch for transmitting or disconnecting power from a motor to wheels and an oil pump driven by the motor to supply oil to the motor, when a magnet temperature of the motor is relatively higher than a predetermined reference temperature at which the motor needs to be cooled, and when a vehicle is determined to be stopped, the clutch is disengaged, and then the motor is driven to drive the oil pump, to thereby supply the oil to the motor to cool the motor (for example, refer to Patent Literature 1).